Methods are generally known. A spiral scan is typically carried out over the heart region to produce an image series of the movement of a heart in the cardiac cycle, the heart being completely scanned over all cycle phases. Further, at least one cardiac cycle is used to reconstruct the cycle timing in a volume illustration.
An ECG is used as a rule to synchronize the recorded image data. It is also possible to determine the movement of the heart exclusively from the detector output data of the computed tomography, and thereby to assign the recorded detector data to the individual cardiac cycle phases and thus combine them to form a complete picture of the heart beyond a typical cardiac cycle. It is possible here to combine data originating from a number of cardiac cycles and, if appropriate, also from a number of X-ray tubes.
For the purpose of better recording and a high-contrast illustration of the cardiac vessels, a contrast medium is usually injected, that circulates in the blood circulation during the scan and provides a sufficiently high-contrast illustration.
A problem with such a cardio scan resides in the fact that, on the one hand, any avoidable radiation dose applied to the patient should be avoided. Even very slight radiation doses can cause lasting damage in the DNA of the cells that can possibly lead to an increased risk of cancer. On the other hand, as the contrast media used may have a damaging effect, the aim is to administer the smallest possible amount of contrast medium.